This invention relates to a dispersible antifoam formulation containing a silicone for incorporation into laundry detergents and which antifoam formulation provides a controlled wash cycle and especially rinse cycle foaming behavior.
Solid detergent formulations are sold in powder or granular form. A disadvantage of solid detergents is that, on account of the hydroscopicity of individual raw materials of the formulation, the solid detergent shows a pronounced tendency towards caking or clumping in the presence of small quantities of moisture. This does not make the detergent unusable, however, because the effect of the individual components of the detergent remain intact even after clumping or caking in the presence of moisture. However, the appearance of the detergent in most cases is diminished. As a result, there has been a desire to develop liquid detergent compositions for use in lieu of conventionally formulated solid detergent compositions. The liquid detergent allows for use of lower washing temperatures inclusive of cold water laundering. Granular detergents have not fully adapted to such variations because of weaknesses in respect of dissolving speed, insolubility, and cleaning efficiency. Due to such problems of caking and the slowness of solid and granular detergents to dissolve, trends in detergent manufacture have leaned toward the liquid detergent. Such detergents usually include an organic surfactant, water, various detergent builder systems, enzymes, bleaches, pH modifiers, and solvents. It is not uncommon to also include an antifoam or defoamer formulation as a part of the detergent package.
A defoamer or antifoam agent is a material which, when added in low concentration to a foaming liquid, controls the foam problem. The defoamer equilibrates the rate of foam collapse with the rate of foam formation Such materials, in addition, remove unsightly and troublesome surface foam, improve filtration, watering, washing, and drainage, of various types of suspensions, mixtures, and slurries. Defoamers have found application traditionally in such areas of use as the pulp and paper industry, paints and latex, coating processes, fertilizers, textiles, fermentation processes, metal working, adhesive, caulk and polymer manufacture, the sugar beet industry, oil well cement, cleaning compounds, cooling towers, and in chemical processes of varied description such as municipal and industrial primary and secondary waste water treatment facilities.
It is essential for a defoamer that it be inert and not capable of reacting with the product or system in which it is used, and that it have no adverse effect on the product or system. The components of a defoamer generally consist of primary and secondary antifoam agents, a carrier, an emulsifier, and optionally a stabilizing agent. The primary antifoam agent is the main ingredient of the defoamer and includes materials such as hydrophobic silicone treated silica, fatty amides, hydrocarbon waxes, and fatty acids and esters. In particular, hydrophobic silica is finely divided silica coated with chemisorbed silicone. The silica is dispersed in hydrocarbon oil and the hydrophobic silica particles present a low energy silicone surface to the foamed environment. In the absence of the hydrocarbon oil, hydrophobic silica itself has no defoaming capacity. The secondary antifoam agent acts synergistically with the primary antifoam agent and includes such materials as silicones, and fatty alcohols and esters. Carriers frequently comprise hydrocarbon oils, water, fatty alcohols and esters, and solvents. Emulsifiers such as esters, ethoxylated compounds, sorbitan esters, silicones, and alcohol sulfates, function to spread or introduce the primary and secondary antifoam agents and the carrier into the system. Shelf life of defoamers can be improved by stabilizing agents, and often in water-based defoamers, a preservative is added to prevent bacterial spoilage in the drum or shipping container. Such stabilizing agents have consisted of, for example, oleic acid, hexylene glycol, fatty alcohols, naphthalene sulfonates, butyl alcohol, and formaldehyde.
The inclusion of a defoamer or antifoam agent in a liquid laundry detergent is not new, however, it is not common. This is for the reason that it is particularly difficult to homogeneously disperse antifoam formulations into aqueous mediums such as liquid laundry detergents. A liquid laundry detergent is a complex formulation chemically and ingredient-wise, and often the complexity of such formulations hinder a homogeneous dispersion of an antifoam composition in the detergent. The result is often loss of clarity seen in hazy formulations, as well as flocculates of antifoam accumulating at the surface of the detergent. The use of antifoams in granular and powdered detergent formulations is taught in a number of references, exemplary of which are, for example, West German published unexamined application (Offenlegungsschrift) No. 2832679 of Feb. 15, 1979; French published unexamined application No. 2285453 of May 21, 1976; European published unexamined application No. 0091802A1 of Oct. 19, 1983; and in U.S. Pat. Nos. 4,400,288, and 4,732,694, issued Aug. 23, 1983 and Mar. 22, 1988, respectively. Typical of liquid type laundry detergent formulations which include an antifoaming agent or suds suppressor can be found in, for example, U.S. Pat. No. 4,075,118, issued Feb. 21, 1978, and in U.S. Pat. No. 4,798,679, issued Jan. 17, 1989. A particularly effective silicone antifoam agent is taught in U.S. Pat. No. 4,639,489, issued Jan. 27, 1987 and in U.S. Pat. No. 4,749,740, issued June 7, 1988. However, in aqueous medium such as liquid laundry detergents, this antifoam like other antifoam formulations has been found to be difficultly dispersible.
Therefore, and in accordance with the present invention, it has been discovered that certain combinations of surfactants and dispersants when included with and incorporated into an antifoam formulation of U.S. Pat. Nos. 4,639,489 and 4,749,740, render the antifoam dispersible in aqueous mediums such as liquid laundry detergents, and therefore solve the problem of dispersibility of the antifoam formulations.
In U.S. Pat. No. 3,784,479, issued Jan. 8, 1974, to Keil, there is disclosed an emulsion or dispersion of a foam control agent in a polyglycol such as polypropyleneoxide, polyethyleneoxide, or copolymers thereof, for use in aqueous systems. However, the aqueous systems in Keil are industrial systems such as alkaline soap solutions, evaporated alkaline paper black liquors, concentrated synthetic rubber latices, steam distilled styrene-butadiene emulsions, refined sugar, dyed textiles, and sewage. An alkaline soap solution cannot be considered a domestic laundry detergent because laundry detergents are not made from soap. Further, except for the non-aqueous polyglycol vehicle in Keil, the surfactants included therein are all silicone type, as compared to the mixed organic and silicone type surfactants of the present invention. In addition, and in contrast to the present invention, Keil fails to teach the inclusion of a secondary antifoam agent, as well as an nonionic organic surfactant. Thus, a laundry detergent can be provided herein and which contains an improved antifoam formulation which is effective in both wash and rinse cycles.